QUEBEC CITY, June 10 (Reuters) - The United States and Canada swung sharply towards a diplomatic and trade crisis on Sunday as top White House advisers lashed out at Canadian Prime Minister Justin Trudeau a day after U.S. President Trump called him “very dishonest and weak.”

The spat drew in Germany and France, who sharply criticized Trump’s decision to abruptly withdraw his support for a Group of Seven communique hammered out at a Canadian summit on Saturday, accusing him of destroying trust and acting inconsistently.

Canadian Foreign Minister Chrystia Freeland responded to the White House assault by saying ad hominem attacks are not helpful, that Canada will retaliate to U.S. tariffs in a measured and reciprocal way and that Canada will always be willing to talk.

“Canada does not conduct its diplomacy through ad hominem attacks ... and we refrain particularly from ad hominem attacks when it comes from a close ally,” Freeland told reporters in Quebec City on Sunday.

Trump’s looming summit with North Korean leader Kim Jong Un heightened tension, and White House economic adviser Larry Kudlow accused Trudeau of betraying Trump with “polarizing” statements on trade policy that risked making the U.S. leader look weak on the eve of the historic North Korea summit.

Hours after Trump withdrew his support for the joint statement and attacked Trudeau, White House economic adviser Larry Kudlow and trade adviser Peter Navarro drove the message home on Sunday morning news shows in an extraordinary assault on a close U.S. ally and neighbor.

“(Trudeau) really kind of stabbed us in the back,” Kudlow, the director of the National Economic Council who had accompanied Trump to the summit of wealthy nations on Saturday, said on CNN’s “State of the Union.”

Navarro told “Fox News Sunday”: “There is a special place in hell for any leader that engages in bad faith diplomacy with President Donald J. Trump and then tries to stab him in the back on the way out the door and that’s what bad-faith Justin Trudeau did with that stunt press conference, that’s what weak dishonest Justin Trudeau did.”

Trudeau did not immediately respond, but his office said on Saturday after Trump withdrew support for the communique that the prime minister had not said anything in his closing news conference he has not said to Trump before.

G7 allies seemed as perplexed as Canada at the sudden diplomatic row, and Germany and France accused Trump of destroying trust and acting inconsistently.

Having left the G7 summit in Canada early, Trump’s announcement on Twitter that he was backing out of the joint communique torpedoed what appeared to be a fragile consensus on a trade dispute between Washington and its top allies.

Trump also said he might double down on import tariffs by hitting the sensitive auto industry, throwing the G7’s efforts to show a united front into disarray.

“In a matter of seconds, you can destroy trust with 280 Twitter characters,” German Foreign Minister Heiko Maas said when asked about Trump’s U-turn, adding it would take much longer to rebuild lost trust.

France is also standing by the G7 communique, a French presidency official said, adding anyone departing from the commitments made at the summit would be showing their “incoherence and inconsistency.”

“International cooperation cannot depend on being angry and on sound bites. Let’s be serious,” the French official, speaking on condition of anonymity, added.

Trump has infuriated the European Union, Canada and Mexico by imposing tariffs on steel and aluminum imports.

Europe’s answer must be to stick even closer together, defend its interests and strengthen alliances with countries such as Japan and Canada, Maas said.

In his news conference, Trudeau had spoken of retaliatory measures that Canada would take next month in response to Trump’s decision to slap tariffs on steel and aluminum imports.

“Canadians are polite, we’re reasonable, but we also will not be pushed around,” Trudeau said. (Additional reporting by David Ljunggren in Quebec City, Doina Chiacu and Sarah Lynch in Washington, Michael Nienaber in Berlin, and Emmanuel Jarry and Dominique Vidalon in Paris; Editing by Meredith Mazzilli)